In general, metallic containers such as an aluminum can and a steel can are widely used as containers for carbonated drinks such as beer, cola, and soda pop or fruit-flavored drinks, various types of tea, canned food and various liquid products.
Such various kinds of metallic containers are provided with a character, a bar code, etc. which display predetermined merchandise information, such as a brand name or ingredients of contents, a producer, a producing district, and a best-before date, for example. This kind of merchandise information is shown by being directly printed on the external surface of a metallic container, or is usually printed on a label and the label is stuck to the external surface of a metallic container.
However, as for the label or printing which displays merchandise information etc., it is common that it is displayed small so that the design or the like of a container is not deteriorated. As a result, the area of a display surface or the character displayed, the number of characters, etc. are limited, and as a result, there was a problem that sufficient merchandise information was not displayed.
Moreover, in the case of bar code display, in order to be read by means of a reader, the bar code itself has to be displayed in a planar form on the container surface. Moreover, reading will become impossible due to the presence of crack, dirt, etc., and since the amount of information which can be coded by a bar code is restricted, the bar code had a certain limit as a means to display and recognize merchandise information as in the case of the display in a character.
Under such circumstances, in recent years, as a means to overcome disadvantageous and inconvenience associated with such conventional merchandise information display, as means for displaying necessary and sufficient merchandise information simply and correctly, an IC tag has come to be used.
An IC tag is called a non-contact IC tag, a RFID (Radio Frequency Identification) tag, RF tag, etc., which is a micro communication terminal which seals an IC chip and a radio antenna with a resin, glass, etc., and is formed in the shape of a tag (baggage tag). Predetermined information is recorded in an IC chip, and the tag is then attached to an object. By picking up the thus recorded information by a reading apparatus (reader/writer) through wireless communication, the information recorded on the IC chip is recognized and displayed.
Such an IC tag can record data (several hundreds bits-several kilobits) in the memory of an IC chip. It can record sufficient information etc. and does not contact the reading equipment, there is no fear of getting crack, dirt, etc., and further, since the tag itself can be used without a power source, processing, downsizing and slimming down thereof can be attained depending on an object to which a tag is attached.
By using such IC tag, various information, including various information about goods, for example, the name or weight of goods, net weight, the name of a manufacturer and a seller, the place and date of manufacture, an expiration date for use, a best-before date, etc., becomes recordable by using such an IC tag. Even for various merchandise information which could not be displayed by a conventional character or a bar code, it became possible to display such information by attaching to a product a tag, which was downsized and became thinner.
When such an IC tag is attached to a metallic container such as an aluminum can or a steel can, the IC tag is adversely affected by the conductivity of the metallic container, and, as a result, a problem occurred accurate wireless communication becomes impossible.
When an IC tag is attached to a container, a magnetic flux which is generated by the IC tag is produced in the direction of penetrating a container. For this reason, when a tag is attached to a metallic container, heat loss etc., which is caused by absorption by the metallic container of magnetic waves and electromagnetic waves emitted by an antenna part arise, whereby communication properties of the tag may be deteriorated.
For example, as shown in FIG. 34(a), when an IC tag 100 is attached to a metallic container 101, as shown in FIG. 34(b), an eddy current is induced on the surface of the metallic container 101 by a magnetic flux emitted by the tag 100. The eddy current cancels the magnetic flux generated by the IC tag 100, and heat loss occurs.
Moreover, the inductance or the like of the antenna coil part of the tag 100 will be changed by the influences of the metallic container 101, whereby the resonance frequency of the resonant circuit of the antenna will also vary.
When a common IC tag which is used widely is attached to a metallic container as it is in this way, a problem arises that a tag malfunctions or wireless communications with a reader-writer cannot be conducted.
Under such circumstances, a proposal was made that, when attaching an IC tag to a metallic container such as an aluminum can or a steel can, the configuration of the IC tag is changed so that it is dedicated to a metallic container, whereby the influence by a metallic container can be avoided (see Patent Documents 1 to 3).
Specifically, as shown in FIG. 35, an IC tag 102 which is dedicated for use in a metallic container which was conventionally proposed has a configuration that a magnetic body (highly permeable magnetic body) 103 and a dielectric body which are formed in sheet form etc. are arranged at the side opposed to the metallic container 101 within the tag. As a result, a magnetic flux emitted by the IC tag 102 is allowed to pass the magnetic body 103, thereby preventing an eddy current from being generated in the metallic container 101.